Switch to containerized infrastructure

.travis.yml

@@ -9,14 +9,13 @@ os:
   - linux
   - osx
 
+sudo: false
+
 install:
   - git clone https://github.com/creationix/nvm.git /tmp/.nvm
   - source /tmp/.nvm/nvm.sh
   - nvm install $NODE_VERSION
   - nvm use $NODE_VERSION
-  - if [ $TRAVIS_OS_NAME == "linux" ]; then
-      sudo apt-get install build-essential git libgnome-keyring-dev fakeroot;
-    fi
 
 script: script/cibuild
 
@@ -24,3 +23,11 @@ notifications:
   email:
     on_success: never
     on_failure: change
+
+addons:
+  apt:
+    packages:
+    - build-essential
+    - git
+    - libgnome-keyring-dev
+    - fakeroot